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BUG: KASAN: slab-out-of-bounds in memcpy include/linux/string.h:406 [inline]
BUG: KASAN: slab-out-of-bounds in scr_memcpyw include/linux/vt_buffer.h:49 [inline]
BUG: KASAN: slab-out-of-bounds in vc_do_resize+0x9d6/0x13f0 drivers/tty/vt/vt.c:1286
Read of size 4 at addr ffff8880a871daa0 by task syz-executor.0/7190

CPU: 1 PID: 7190 Comm: syz-executor.0 Not tainted 5.8.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x18f/0x20d lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xae/0x436 mm/kasan/report.c:383
 __kasan_report mm/kasan/report.c:513 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
 check_memory_region_inline mm/kasan/generic.c:186 [inline]
 check_memory_region+0x13d/0x180 mm/kasan/generic.c:192
 memcpy+0x20/0x60 mm/kasan/common.c:105
 memcpy include/linux/string.h:406 [inline]
 scr_memcpyw include/linux/vt_buffer.h:49 [inline]
 vc_do_resize+0x9d6/0x13f0 drivers/tty/vt/vt.c:1286
 fbcon_modechanged+0x36c/0x710 drivers/video/fbdev/core/fbcon.c:2990
 fbcon_update_vcs+0x3a/0x50 drivers/video/fbdev/core/fbcon.c:3048
 fb_set_var+0xae8/0xd60 drivers/video/fbdev/core/fbmem.c:1056
 do_fb_ioctl+0x33f/0x6c0 drivers/video/fbdev/core/fbmem.c:1109
 fb_ioctl+0xdd/0x130 drivers/video/fbdev/core/fbmem.c:1185
 vfs_ioctl fs/ioctl.c:48 [inline]
 ksys_ioctl+0x11a/0x180 fs/ioctl.c:753
 __do_sys_ioctl fs/ioctl.c:762 [inline]
 __se_sys_ioctl fs/ioctl.c:760 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:760
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45c429
Code: 8d b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 5b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f73c4db1c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 000000000000d540 RCX: 000000000045c429
RDX: 0000000020000000 RSI: 0000000000004601 RDI: 0000000000000005
RBP: 000000000078bf40 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000078bf0c
R13: 00007ffdce76309f R14: 00007f73c4db29c0 R15: 000000000078bf0c

Allocated by task 6740:
 save_stack+0x1b/0x40 mm/kasan/common.c:48
 set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc.constprop.0+0xc2/0xd0 mm/kasan/common.c:494
 __do_kmalloc mm/slab.c:3656 [inline]
 __kmalloc+0x17a/0x340 mm/slab.c:3665
 kmalloc include/linux/slab.h:560 [inline]
 kernfs_fop_write+0x345/0x490 fs/kernfs/file.c:292
 vfs_write+0x2b0/0x6b0 fs/read_write.c:576
 ksys_write+0x12d/0x250 fs/read_write.c:631
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 6740:
 save_stack+0x1b/0x40 mm/kasan/common.c:48
 set_track mm/kasan/common.c:56 [inline]
 kasan_set_free_info mm/kasan/common.c:316 [inline]
 __kasan_slab_free+0xf5/0x140 mm/kasan/common.c:455
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x103/0x2c0 mm/slab.c:3757
 kernfs_fop_write+0x300/0x490 fs/kernfs/file.c:329
 vfs_write+0x2b0/0x6b0 fs/read_write.c:576
 ksys_write+0x12d/0x250 fs/read_write.c:631
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff8880a871da80
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 0 bytes to the right of
 32-byte region [ffff8880a871da80, ffff8880a871daa0)
The buggy address belongs to the page:
page:ffffea0002a1c740 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff8880a871dfc1
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea0002a1f3c8 ffff8880aa001240 ffff8880aa0001c0
raw: ffff8880a871dfc1 ffff8880a871d000 0000000100000038 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a871d980: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff8880a871da00: 00 04 fc fc fc fc fc fc fb fb fb fb fc fc fc fc
>ffff8880a871da80: fb fb fb fb fc fc fc fc 00 00 01 fc fc fc fc fc
                               ^
 ffff8880a871db00: 00 00 fc fc fc fc fc fc fb fb fb fb fc fc fc fc
 ffff8880a871db80: 00 00 01 fc fc fc fc fc fb fb fb fb fc fc fc fc
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